Surface immunoglobulin receptors of rabbit lymphoid cells. Evaluation of fluorescent staining with antibodies to immunoglobulin light chain allotypes

Cross-reaction of a monoclonal antibody to human MHC class II molecules with rabbit B cells

Monoclonal antibodies, 21w4 and 44H10, against human MHC class II determinants, were analysed for their reactivity with rabbit lymphoid cells. Both MAb bind to all human B lymphoblastoid lines, irrespective of their HLA-DR phenotype. HLA-DR antigens, purified by affinity to 21W4 IgG Sepharose, can be precipitated with 44H10 MAb, indicating that both antibodies react with the same molecules. Competitive inhibition studies with purified MAb IgG show that 44H10 and 21w4 recognize different epitopes of HLA-DR molecules. The 21w4 MAb, previously shown to cross-react with cells of pig, mouse and sheep, does not react with rabbit lymphoid cells. The 44H10 MAb binds to lymphoid cell suspensions prepared from rabbit appendix, spleen and mesenteric lymph nodes. Its reactivity correlates with that of RABELA, a polyclonal antibody specific for rabbit B cells. Mesenteric lymph node and spleen cell suspensions, depleted of sIg+ cells, are devoid of 44H10+ cells, while similarly-treated appendix B cells still contain a subset of B cells which are sIg-, RABELA+ and 44H10+. These studies thus report on the presence of MHC class II determinants on rabbit B cells, cross-reacting with human HLA-DR.

Fluorescence-activated cell sorter (FACS) analysis of rabbit cells

Monoclonal antibodies RB1, RB2, RT1, RT2 and RB3 were prepared against rabbit lymphoid cells by immunization with various fractions of rabbit lymphoid cells. The antigens detected by the antibodies are found on B and T cells in different densities. High proportions of polymorphonuclear and bone marrow cells which do not carry the RABELA and RTLA antigens carry the antigens of the RB and RT series. A subpopulation of appendix sIg-negative, RTLA-negative cells has a relatively high concentration of RT2. In general, B and T cells of the appendix show relatively small differences in the membrane densities of RB and RT antigens.

A comparison of regulatory cells from rabbit spleen and appendix

Both spleen and appendix of the rabbit contain two types of accessory cells that regulate the response of T-cells to concanavalin A. These accessory cells are found among non-T, non-B adherent cells and among B-cells. There is, so far, no evidence for a sequential interaction of these two cell types. In addition, there is an inhibitory adherent cell type in the appendix that interferes with the B-cell-regulated proliferative T-cell response.

Rabbit spleen B lymphocytes as helper cells in lymphocyte activation by concanavalin A and phytohaemagglutinin

Using rosetting methods, we have purified rabbit B cells and studied their interactions with T cells purified by passage over an anti-immunoglobulin-coated Degalan beads column. B cells enhance the response of T cells to concanavalin A (Con A) and phytohaemagglutinin. In regulation of the response to Con A, an adherent cell is a third participating cell. B-cell preparation contain a minority of cells that can respond to T mitogens with the help of non-proliferating T cells, but the proportion of these responding cells is small, and the involvement of the T-cell impurity cannot be excluded.

Relative expression of light-chain allotypic specificities on the surface of rabbit lymphocytes as a function of age

Lymphoid cells of heterozygous Ab4/Ab9 rabbits of various ages were stained with fluorescent anti-allotype antibodies. In foetal and newborn rabbits, the percentage of Ab-positive cells in low; it increases with age, reaching the adult value when the animals are 100 days old. The rate of increase in the percentage of Ab4-positive cells is higher than in that of Ab9-positive cells. Thus, the Ab4/Ab9 ratio, which is initially 1, increases with age and reaches 2.2. in spleen and 4 in appendix of young adult animals. We conclude that the change in Ab4/Ab9 ratio is due to differential clonal expansion which we attribute to charge-related differences in the ability of Ab4 and Ab9 receptor-bearing cells to capture antigen when environmental antigens are encountered in postnatal life.